One of the best applications I've downloaded to help with my iTunes collection. I am extremely OCD about my iTunes library as well, but I don't feel like paying for fixTunes. I found something else to help with something I'm a bit obsessive over. I absolutely have to have lyrics to my songs whenever possible and with over 3000 songs, it's irritating to put in so many Google searches.

GimmeSomeTune does an automatic search for every song without lyrics as soon as it begins playing. It also searches for Album art as well. It's totally free (although they do ask for an optional donation).